Book holder



FIG. 1 is a top view of the book holder according to the present design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a back elevational view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a left side elevational view thereof; and,

FIG. 6 is a right side elevational view thereof. 

The ornamental design for a book holder, as shown and described. 